It's my understanding the united front ceased to exist functionally after 1941. There was that big incident where Chiang Kai-shek ordered two communist divisions to go north of the Yangtze river, but once they got there they got ambushed by nationalist forces.

Except the effect of this was Chinese civilians simply heard "Chinese government betrays and shoots Chinese soldiers who were doing their job" when everyone was supposed to be on the same side against Japan. So I have to imagine that incident got a lot of everyday Chinese people interested in revolution